Stimuli-Responsive Drug Delivery System: Current Application in Osteoarticular Diseases and Future Directions

Inflammatory arthritis, which mainly involves rheumatoid arthritis (RA) and osteoarthritis (OA), is a group of diseases characterized by joint inflammation, pain, and disability. Traditional drug delivery approaches (ointments, capsules, tablets, etc.) have many deficiencies in drug stability, target effect, sustained release, and sufficient drug concentration at the desired sites. The lack of an effective delivery approach can affect the integrality of the entire therapeutic process. Stimuli-responsive drug delivery systems consisting of smart nanomaterials respond to specific internal or external stimuli, which may achieve controlled and precise drug release. Utilizing these appropriate triggers such as pH, reactive oxygen species (ROS), and enzymes, therapeutic drugs can be released specifically within the joints and bone tissues, to promote bone repair and improve synovitis in inflammatory joints. This chapter highlighted the advancements in stimulus-responsive nano-drug delivery systems with design considerations, classifications, and drawings, discussed their applications in the treatment of inflammatory arthritis and bone defects, and explored the challenges and future directions in controlled drug delivery.